Added-Mass Effect in Modeling of Cilia-Based Devices for Microfluidic Systems

This article shows that the added mass due to fluid structure interaction significantly affects the vibrational dynamics of cilia-based devices. Our main contribution is to show that such damping effects cannot explain the substantial reduction in the resonant vibrational frequency of the cilia operating in liquid when compared to the natural frequency of the cilia in air. It is shown that an added-mass approach (that accounts for the inertial loading of the fluid) can explain this reduction in the resonant vibrational frequency when operating the cantilever-type devices in liquids. Additionally, it is shown that the added-mass effect can explain why the cilia-vibration amplitude is not substantially reduced in a liquid by the hydrodynamic drag force. Thus, this article shows the need to model the added-mass effect, both, theoretically and by using experimental results.